Packet forwarding is a process of relaying packets from one communication link to another by nodes in a network. A packet is a formatted unit of data that typically contains control information and payload data. Control information may include: source and destination IP addresses, error detection codes like checksums, sequencing information, etc. Control information is typically found in packet headers and trailers, with payload data in between. Network nodes may take form in one or more routers, one or more bridges, one or more switches, or any other suitable communications processing device.
Segment routing can be used to forward packets. Segment routing utilizes segments, which act as multi-hop or single-hop paths. Two types of segments include nodal segments and adjacency segments. A nodal segment represents a path to a node and can be a one-hop or a multi-hop path. Packets addressed with a given nodal segment ID typically travel along a shortest path to the node represented by the segment ID. An adjacency segment represents a specific one-hop path to a node.